The temporary absence of EMV Express Transit in iOS 12.4 betas 1~3 has ended, the option has finally returned in iOS 12.4 public beta 4 (16G5046d). OMNY users in New York can use the beta for transit now, but since OMNY itself is one big beta system why bother with beta on beta? I think it’s better to wait for the official release. Portland HOP iPhone users need not bother as they can put real HOP card in Wallet. It’s way better than using a credit card, faster and cheaper too.
The only question remaining is, what kind of Wallet grunt work were they up that they had to remove EMV Express Transit temporarily in the first place?